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module Lib
def self.compute_variance( old_variance, n, new_mean, old_mean, new_value )
# use revursiv formular for computing the variance
# ( see Tysiak, Folgen: explizit und rekursiv, ISSN: 0025-5866
# http://www.frl.de/tysiakpapers/07_TY_Papers.pdf )
return (n>1 ? old_variance * (n-2)/(n-1) : 0) +
(new_mean - old_mean)**2 +
(n>1 ? (new_value - new_mean)**2/(n-1) : 0 )
end
module MergeObjects
@@merge_count = {}
@@avg_attributes = {}
@@sum_attributes = {}
@@non_numeric_attributes = {}
def self.merge_array_objects( array )
return nil if array.size == nil
return array[0] if array.size==1
m = self.merge_objects(array[0], array[1])
(2..array.size-1).each do |i|
m = self.merge_objects(m, array[i] )
end
return m
end
def self.merged?(object)
return merge_count(object)>1
end
def self.merge_count( object )
@@merge_count[object] = 1 if @@merge_count[object]==nil
return @@merge_count[object]
end
def self.merge_objects( object1, object2 )
raise "classes not equal : "+object1.class.to_s+" != "+object2.class.to_s if object1.class != object2.class
object_class = object1.class
raise "register which attributes to merge first, nothing found for class "+object_class.to_s unless merge_attributes_registered?(object_class)
raise "not supported, successivly add unmerged object to a merge object" if merge_count(object2)>1
new_object = object_class.new
# actually instance_variables would be appropriate, but the datamanager creates objects dynamically
object1.public_methods.each do |method|
v = method.to_sym
if merge_attribute?(object_class, v)
old_variance = (avg_attribute?(object_class,v) and variance_attribute?(new_object,v)) ? object1.send(variance_symbol(v)) : nil
m = merge_value( object_class, v, object1.send(v), object2.send(v), merge_count(object1), old_variance )
new_object.send("#{v.to_s}=".to_sym, m[:value])
new_object.send("#{v.to_s}_variance=".to_sym, m[:variance]) if (m[:variance] and variance_attribute?(new_object,v))
end
end
set_merge_count(new_object,merge_count(object1)+1)
return new_object
end
def self.register_merge_attributes( object_class, avg_attributes, sum_attributes, non_numeric_attributes)
@@avg_attributes[object_class] = avg_attributes + avg_attributes.collect{ |a| (a.to_s+"_ranking").to_sym }
@@sum_attributes[object_class] = sum_attributes
@@non_numeric_attributes[object_class] = non_numeric_attributes
end
def self.merge_attributes_registered?( object_class )
[ @@avg_attributes, @@sum_attributes, @@non_numeric_attributes ].each{ |map| return false unless map.has_key?(object_class) }
return true
end
protected
def self.merge_value( object_class, attribute, value1, value2, weight1=1, variance1=nil )
variance = nil
if (avg=avg_attribute?(object_class, attribute)) || sum_attribute?(object_class, attribute)
# we string to numerics if wanted, value1 is no string anymore if weight>1
if value2.is_a?(String) and ((weight1==1 and value1.is_a?(String)) or (weight1>1 and value1.is_a?(Numeric)))
value1 = value1.to_f
value2 = value2.to_f
end
if (value1==nil and value2==nil )
#do nothing
elsif value1.is_a?(Numeric) and value2.is_a?(Numeric)
if avg
value = (value1 * weight1 + value2) / (weight1 + 1).to_f;
variance = Lib::compute_variance( variance1!=nil ? variance1 : 0, weight1+1, value, value1, value2 )
else
value = value1 + value2
end
elsif value1.is_a?(Array) and value2.is_a?(Array)
raise "cannot merge arrays with unequal sizes" if !value2.is_a?(Array) || value1.size!=value2.size
value = []
variance = [] if avg
(0..value1.size-1).each do |i|
if avg
value << (value1[i] * weight1 + value2[i]) / (weight1 + 1).to_f;
variance << Lib::compute_variance( (variance1!=nil && variance1[i]!=nil) ? variance1[i] : 0, weight1+1, value[-1], value1[i], value2[i] )
else
value << value1[i] + value2[i]
end
end
elsif value1.is_a?(Hash) and value2.is_a?(Hash)
value = {}
variance = {} if avg
value1.keys.each do |k|
if avg
value[k] = (value1[k] * weight1 + value2[k]) / (weight1 + 1).to_f;
variance[k] = Lib::compute_variance( (variance1!=nil && variance1[k]!=nil) ? variance1[k] : 0, weight1+1, value[k], value1[k], value2[k] )
else
value[k] = value1[k] + value2[k]
end
end
else
raise "invalid, cannot avg/sum non-numeric content for attribute: "+attribute.to_s+" contents: '"+value1.to_s+"' ("+
value1.class.to_s+"), '"+value2.to_s+"' ("+value2.class.to_s+")"
end
elsif non_numeric_attribute?(object_class, attribute)
if (value1.is_a?(Hash) and value2.is_a?(Hash))
value = {}
value1.keys.each do |k|
if merge_attribute?(object_class, k)
m = merge_value( object_class, k, value1[k], value2[k], weight1, (variance1!=nil ? variance1[k] : nil) )
value[k] = m[:value]
value[variance_symbol(k)] = m[:variance] if m[:variance]
end
end
elsif value1.is_a?(Array)
raise "non-numerical arrays not yet supported"
else
if value1==nil && value2==nil
value = nil
elsif value1.to_s != value2.to_s
value = value1.to_s + ";" + value2.to_s
else
value = value2.to_s
end
end
else
raise "invalid type '"+attribute.to_s+"'"
end
{:value => value, :variance => variance }
end
def self.set_merge_count(object, merge_count)
@@merge_count[object] = merge_count
end
def self.avg_attribute?(object_class, attribute)
return @@avg_attributes[object_class].index(attribute) != nil
end
def self.sum_attribute?(object_class, attribute)
return @@sum_attributes[object_class].index(attribute) != nil
end
def self.non_numeric_attribute?(object_class, attribute)
return @@non_numeric_attributes[object_class].index(attribute) != nil
end
def self.merge_attribute?(object_class, attribute)
return avg_attribute?(object_class, attribute)||
sum_attribute?(object_class, attribute) ||
non_numeric_attribute?(object_class,attribute)
end
def self.variance_symbol(attribute)
return (attribute.to_s+"_variance").to_sym
end
def self.variance_attribute?(object, attribute)
return false unless avg_attribute?(object.class, attribute)
begin
return object.respond_to?( variance_symbol(attribute) )
rescue
return false
end
end
end
class MergeTest
attr_accessor :string, :integer, :float, :hash_value, :float, :float_array, :float_variance, :float_array_variance, :is_nil
AVG = [:float, :float_array, :int_key ]
SUM = [:integer ]
ELSE = [:string, :hash_value, :is_nil]
def to_s
res = [:is_nil, :string, :integer, :float, :hash_value, :float_array].collect do |var|
variance = nil
begin
variance = "+-"+send((var.to_s+"_variance")).inspect if AVG.index(var)!=nil
rescue
end
var.to_s+":"+send(var).inspect+variance.to_s
end
res.join(" ")
end
def self.demo
to_merge = []
p = MergeTest.new
p.string = "asdf"
p.integer = 39
p.float = 78.6
p.float_array = [1, 2]
p.hash_value = {:mixed_key=>80, :string_key=>"tu", :int_key=>70}
to_merge << p
p = MergeTest.new
p.string = "jkl"
p.integer = 25
p.float = 35.6
p.float_array = [1, 3]
p.hash_value = {:mixed_key=>"bla", :string_key=>"iu", :int_key=>34}
to_merge << p
p = MergeTest.new
p.string = "qwert"
p.integer = 100
p.float = 100
p.float_array = [2, 3]
p.hash_value = {:mixed_key=>45, :string_key=>"op", :int_key=>20}
to_merge << p
puts "single:\n"+to_merge.collect{|t| t.to_s+"\n"}.to_s+"\n"
MergeObjects.register_merge_attributes(to_merge[0].class, AVG, SUM, ELSE)
puts "merged:\n"+MergeObjects.merge_array_objects(to_merge).to_s
end
end
end
#Lib::MergeTest.demo
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